3D Modeling for Crime Scenes

When people think of 3D modeling most would think of using it for movies and TV or for the production of a product. I have done some 3D modeling at ISU and I was interested in learning more about it. After some research I found an article that discussed how professional modelers are being used to help convict murders.

After there is a crime scene and pictures are taken, they use the images to form an entire crime scene which forensics can then use to solve the murder. For example here is a video of a 3D model of the assassination of JFK. Though you might think this is a poor example of using 3D modeling because we are not exactly sure who murdered JFK, it has helped us find more information about what happened that day.

Furthermore if anyone has ever seen the TV show Dexter they would understand this topic more. Dexter is a blood spatter analysis. He uses string attached from a focal point on the splatters of blood to assume where the murderer was standing. As you can watch in this video the techniques they use to see the different types of patterns that weapons leave, and the string analysis that I talked about earlier at the end of the clip.

The spatter analysis can take this to a professional 3D modeler who can bring it into the computer to see it in better detail. According to the article “The first step is to use a laser scanner to make a 3D digital map of every object in the crime scene.The team also uses a digital camera to capture the shape of bloodstains. They then use another laser ranging device called a tachymeter to obtain a precise location for each blood spot in the 3D model.

Next, they calculate the mass of each drop from the size of its stain, and use this to calculate its maximum potential velocity – air drag would rip apart a droplet if it travelled faster than this limit. With that information, and an angle of impact estimated from the shape of the stain, their software projects a realistic trajectory backwards in time to locate the origin of the blood spatter. The 3D results give us good clues about the area of origin, the number of blows, the positioning of the victim and the sequence of events. The system has already helped in two murder inquiries, revealing in one that a woman killed by her husband was lying in bed rather than sitting up when attacked.”